The present invention relates to a novel and useful medicinal powder delivery system.
Drugs are often delivered in powder form to the lungs of patients, such as asthmatics, and powder medicaments offer several advantages over liquid drugs suspended in propellants in that powder medicaments are premixed and dosages of the same may be more accurately controlled. Also, powder medicaments are easier to manufacture and distribute since refrigeration is not often required.
Several problems arise with the use of powder medicaments. For example, it is essential that powders do not re-agglomerate before or at the time of delivery. Ideally, the delivery of powder medicaments should be in a xe2x80x9csoft cloudxe2x80x9d or homogeneous aerosol in which the particles constituting the powder remain separated, reagglomeration of particles into larger entities renders the powder as an incompatible entity to the alveolar tissue in the lungs. In other words, agglomerated powder medicaments act as irritants to the respiratory system. Typically, prior systems have mixed propellants with powder medicaments prior to delivery of the drug resulting in reagglomeration during storage or delivery of the mixture.
Also, it is important that powder medicaments not be contaminated before application to the lungs of a patient. Prior art systems employing fans and the like expose powder medicaments to potential contaminants during the delivery and storage process.
In addition, it is imperative that a constant and total dose of powder medicament be delivered to a patient in order to achieve a high percentage of absorption of the powder medicament by the alveolar tissue of the lungs. Again, the prior systems have not accomplished this result since dosage depends on various factors such as propellant pressure, timing, and velocity of propellant/powder streams, the ease of use, patient inhalation ability and the like. Also, many prior art powder drug delivery systems use gun-like mechanisms which create a high degree of stress on a patient, making them unsuitable in many cases.
A medicinal powder delivery system which is effective in safely and conveniently delivering drugs would constitute a remarkable advance in the medical field.
In accordance with the present invention a novel and useful medicinal powder delivery system is herein provided.
The system of the present invention is used in conjunction with minimal quantities of a gaseous propellant of known characteristics. The system includes a nozzle having an entrance and exit for passing medicinal powder material through the same. The nozzle may be mounted or supported in a housing in a compact manner.
A conduit is also employed in the present invention and includes an entrance and exit for passage of a conventional gaseous propellant. The exit of the conduit lies adjacent the nozzle exit within the housing. In addition, the propellant is directed through means for shaping the flow of the characteristics of the gaseous propellant emanating from the gaseous propellant source and exiting the conduit. In this regard a stable vortex field is produced which creates a relatively high vacuum. Such means may take the form of a tube which includes an inner bore and an outer surface. The outer surface of the tube communicates with the conduit and may be formed with a plurality of recesses which interact with the propellant emanating from the gaseous propellant source and traveling through the gaseous propellant conduit. Each recess may be formed into one having a triangular cross-sectional configuration. The bore of the tube may further possess a first portion communicating with the nozzle exit and a second portion serving as an outflow for the powder medicament. In other words, the tube bore permits passage of the medicinal powder from the nozzle exit and outwardly from the tube bore. Most importantly, the outer surface of the tube possessing such means for shaping the flow characteristics of the propellant lies immediately adjacent the outflow of the tube.
A vessel having a chamber receives the outflow of powder medicament from the tube bore and the propellant flowing from the means for shaping the flow characteristics of the same. The gaseous propellant and the powder medicament are mixed in the chamber and expanded in the vessel. In this regard, the vessel may include an adjacent larger chamber having one or more vent openings to further mix the powder medicament and the gaseous propellant with air in the form of a homogeneous aerosol. The vessel includes an exit permitting egress of the medicinal powder, air, and relatively small amounts of propellant for delivery to a patient. The exit may include a plastic or elastomeric member having an opening of oval cross-sectional configuration to further control the movement of the aerosol.
Another aspect of the present invention concerns the storage and metering of the medicinal powder. In this regard, a support having a channel and an aperture may be formed on the housing to allow the aperture of the support to communicate with the entrance to the nozzle. The channel is intended to slidable engage items motivated therethrough.
A cartridge is also employed in the present invention and is sized to slidingly engage or be guided along the channel of the support. The cartridge includes a container having cavity for retaining a predetermined dose of the medicinal powder. Movement of the cartridge along the channel permits the cavity of the cartridge to align with the aperture of the support for the channel. Moreover, a cover may be placed on the cartridge to cover the cavity containing the powder drug to maintain sterility and to prevent contamination of the medicament. The support may further comprise means for removing the cover to permit the cavity to communicate directly with the aperture of the support channel. Such means may take the form of an edge on the channel which engages the cover and peels off the same continuously as the cartridge is advanced along the channel until alignment of the cavity and the aperture of the channel occur. At this juncture, the mere injection of gaseous propellant into the system of the present invention will educe or draw powder medicament from the cavity of the cartridge, mix the powder medicament with the propellant and air for delivery of a measured dose to the user in the form of a low velocity, soft, evenly dispersed aerosol.
It may be apparent that a novel and useful medicinal powder delivery system has been hereinabove described.
It is therefore an object of the present invention to provide a medicinal powder delivery system which delivers powder drugs in a homogeneous aerosol that is easy to administer to a patient.
Another object of the present invention is to provide a medicinal powder delivery system which eliminates reagglomeration of powder medications in alveolar tissue.
Yet another object of the present invention is to provide a medicinal powder delivery system which is capable of delivering drugs in powder form absent contamination.
A further object of the present invention is to provide a medicinal powder delivery system which accurately meters the powder drug to produce an accurate and reproducible dose level of the same to the user.
A further object of the present invention is to provide a medicinal powder delivery system in which a conventional gaseous propellant is employed to maintain dispersion of the powder medication prior to use by a patient.
Another object of the present invention is to provide a medicinal powder delivery system which is easily controlled by the injection of gaseous propellant into the system.
Another object of the present invention is to provide a medicinal powder delivery system in which powder drugs are motivated at a controlled flow rate and are electrostatically charged to maintain the dispersion of such particles in an aerosol created thereby.
Another object of the present invention is to provide a medicinal powder delivery system in which premixing of the powder drug and the propellant is eliminated.
Another object of the present invention is to provide a medicinal powder delivery system in which the powder drug is loaded into a cartridge and sealed against contamination until activation of the system of the present invention.
Another object of the present invention is to provide a medicinal powder delivery system in which the powder drug ingestion is easily synchronized with the breathing of the patient.
Another object of the present invention is to provide a medicinal powder delivery system which does not require the employment of electric motors or pumps to operate.
Another object of the present invention is to provide a medicinal powder delivery system which is formed into a compact configuration.
Another object of the present invention is to provide a medicinal powder delivery system which is capable of self-cleaning.
Another object of the present invention is to provide a medicinal powder delivery system which operates in an efficient manner and does not waste powdered medicine.
Another object of the present invention is to provide a medicinal powder delivery system which employs a stable vortex eddy field to create a homogeneous aerosol using a powder drug as the solid component.
Another object of the present invention is to provide a medicinal powder delivery system which does not require special training of the user patient to employ the same.
Another object of the invention is to provide a medicinal powder delivery system which facilitates dose counting.
The invention possesses other objects and advantages especially as concerns particular characteristics and features thereof which will become apparent as the specification continues.